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</o:shapelayout></xml><![endif]--></head><body lang=NL link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>My function in Haskell takes a CString and returns a ByteString (of Word8). <o:p></o:p></p><p class=MsoNormal>I tried to put this function in a Haskell made Windows dll. I want to use this function in a program written in C. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The most simple program that compiled was:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Import qualified B.ByteString as B<o:p></o:p></p><p class=MsoNormal>import Foreign.StablePtr<o:p></o:p></p><p class=MsoNormal>import Foreign.C.String<o:p></o:p></p><p class=MsoNormal>import Foreign.Ptr<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>foreign export stdcall parseRuitType :: CString -> IO (Ptr ()) <o:p></o:p></p><p class=MsoNormal>parseRuitType s = do<o:p></o:p></p><p class=MsoNormal> p <- (newStablePtr ( B.pack [10,11,12]))<o:p></o:p></p><p class=MsoNormal> return $ castStablePtrToPtr p<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>For testing I ignore s.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>In the C-program :<o:p></o:p></p><p class=MsoNormal>hs_init(NULL,NULL)<o:p></o:p></p><p class=MsoNormal>res = parseRuitType (“5” )<o:p></o:p></p><p class=MsoNormal>No errors, but the returned value res (or the dereferenced res) makes no sense (not 10,11,12).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My idea was: the result of the function(a ByteString of Word8) must be locked. No garbage collection. But newStablePtr does not return a pointer. So I have to convert the newStablePtr to a real pointer and then coerce this in the C program to a pointer to a array of word8…?<o:p></o:p></p><p class=MsoNormal>I’ve tried to return the ByteString in the Haskell function. But now the compiler complains: Unacceptable result type in foreign declaration : B.ByteString<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’am missing the big picture. Any ideas?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Greetings<o:p></o:p></p><p class=MsoNormal>Kees<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>